This book constitutes the proceedings of the 4th International Workshop on Interaction and Player Research in Game Development, WIPlay 2025, which took place in Belo Horizonte, Brazil, in September 2025. The 10 full papers and 2 full papers included in this book were carefully reviewed and selected from 15 submissions. They were organized in topical sections as follows: Socially Conscious and inclusive game design; ethical game design and responsible gaming; and practical methods and frameworks for game design and evaluation.